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Welcome to Lachlan Cranswick's Personal Homepage in Melbourne, Australia

Using the Davis CarChipEX for computer diagnostics on a 1999 Subaru Legacy (using the OBDII connector)

Getting to and things to do in the Deep River, Upper Ottawa Valley, Ontario, Canada area

Lachlan's Deep River homepage is at http://lachlan.bluehaze.com.au/chalk_river/

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Davis CarChipEX

  • The Davis CarChipEX (and Davis CarChip) can tell you want the 'check engine' light means, and give you the trouble code and a brief description. It can also reset the 'check engine' light."

  • Davis CarChip/CarChipEX: http://www.davisnet.com/drive/products/carchip_products.asp

  • Impatiently opening the box from Davis . The CapChip kit provided from Davis . Serial port connector . Davis CarChip (standard) with connector . Davis CarChip (standard) with connector . Blurred Davis CarChip (standard) with data port showing

  • If you don't have a serial port connected on your computer (many modern laptops do not have this), you will have to get a USB to serial adapter with the CarChip.

  • Be wary that the standard CarChip only logs vehicle trouble codes (check engine light codes) and speed.

  • The CarChipEX can log vehicle trouble codes (check engine light codes), speed, and 4 out of 23 selectable parameters including RPM; Throttle position ; Engine load ; Fuel pressure ; Fuel system status ; Short- and long-term-fuel trim ; Battery voltage ; Timing advance ; Coolant temperature ; Air flow rate ; Intake air temperature ; Intake manifold pressure ; Oxygen sensor voltage ;

    The 1999 Subaru Legacy does not log some of these parameters such as i) intake air temperature; ii) Fuel Pressure; only logs 2 of the fuel trim parameters: Short Term Fuel Trim B1 and Long Term Fuel Trim B1; and only 2 of the 8 Oxygen inputs are supported (B1, S1; and B1, S2).

  • National OBD Clearing House at Weber State University.: http://www.autocenter.weber.edu/OBD-CH/vehicleoems.asp

  • Do Your Own Automotive Diagnostics: http://www.davisnet.com/news/press/drive/files/PC_Toys_Chpt_9.PDF


Images showing where to find the place the OBDII connector in a 1999 Subaru Legacy

The National OBD Clearing House at Weber State University at http://www.autocenter.weber.edu/OBD-CH/vehicleoems.asp lists where the connectors are in the various car models available.

1999 Subaru Legacy . 1999 Subaru Legacy and red arrow points to OBDII connector . Davis CarChip in the 1999 Subaru Legacy OBDII port . Davis CarChip in the 1999 Subaru Legacy OBDII port . 1999 Subaru Legacy and red arrow points to OBDII connector


Example Log Plots generated by Davis CarChipEX

(this is supported by Standard CarChip, except speed vs time plots)

Davis CarChip Graph of Car Speed . Davis CarChip Graph of Short Term Fuel Trim . Davis CarChip Graph of Long Term Fuel Trim

Car Speed; Short Term Fuel Trim; Long Term Fuel Trim


Davis CarChip Graph of Car Speed . Davis CarChip Graph of Fuel System Status . Davis CarChip Graph of Air Flow Rates (kg/s) . Davis CarChip Graph of Engine Speed (RPM)

Car Speed; Fuel System Status; Air Flow Rates (kg/s); Engine Speed (RPM)


Davis CarChip Graph of Car Speed . Davis CarChip Graph of Coolant Temperature . Davis CarChip Graph of Short Term Fuel Trim . Davis CarChip Graph of Battery Voltage . Davis CarChip Graph of Oxygen Sensor B1, S1

Car Speed; Coolant Temperature; Short Term Fuel Trim; Battery Voltage


Davis CarChip Graph of Car Speed . Davis CarChip Graph of Oxygen Sensor B1, S1 . Davis CarChip Graph of Oxygen Sensor B1, S2

Car Speed; Oxygen Sensor B1, S1; Oxygen Sensor B1, S2


What a Trouble Code can look like

View / Vehicle Trouble Log / Summary    

                       Time              Vehicle     Trouble Code     Description
                         
     Problem 1     19/02/2004  16:43     Mel's Honda    P1491     
             Unknown Powertrain DTC (Manufacturer Controlled; Auxiliary Emission Controls)

Details of the Trouble Code

View / Vehicle Trouble Log / Record Problem 1
Overview
     Time :     19/02/2004 16:43
     Vehicle :     Mel's Honda
     CarChip :     J-9889-A
     Trouble Code :     P1491
     Description :     Unknown Powertrain DTC (Manufacturer Controlled; Auxiliary Emission Controls)
     Comments :     
Engine Status
     Fuel Pressure (Gage) :     
     Intake Manifold Pressure (Absolute) :     51 kPa
     Engine Coolant Temperature :     46.00 C
     Calculated Load Value :     50.6 %
     Engine Speed :     1,764 RPM
     Vehicle Speed :     78 kph
Fuel Trim Status
     Short-Term Fuel Trim (Bank 1) :     13.28 %
     Short-Term Fuel Trim (Bank 2) :     
     Long-Term Fuel Trim (Bank 1) :     0.00 %
     Long-Term Fuel Trim (Bank 2) :     
Fuel System Status
     Fuel System 1 Status :     
     Fuel System 2 Status :     Closed loop; using oxygen sensor(s) as feedback for fuel control.


Correlating the trouble code with loggable data from a Davis CarChipEX

In the above case, systematically going through the loggable data shows the Long Term Fuel trim seems to always be at 0.00 %. (logging of Short-Term Fuel Trim (Bank 2) and Long-Term Fuel Trim (Bank 2) are not supported by the vehicle)


View / Trip Log / Record Trip 2
     Vehicle :     Mel's Honda
     CarChip :     J-9889-A

     Start Time :     19/02/2004 16:42
     End Time :     19/02/2004 16:56
     Duration :     00:14:31
          Idle :     00:00:00
          0 to 72 kph :     00:05:02
          72 to 97 kph :     00:07:55
          97 to 121 kph :     00:01:34
          Over 121 kph :     00:00:00

     Distance :     18.2 km
     Average Speed :     75 kph
     Maximum Speed :     107 kph

     Hard Brakes :     1 (Between 0.28 G and 0.48 G)
     Extreme Brakes :     0 (Over 0.48 G)
     Hard Accelerations :     0 (Between 0.28 G and 0.48 G)
     Extreme Accelerations :     0 (Over 0.48 G)

     Parameters
          Parameter 1 :     Vehicle Speed Every 5 Seconds
          Parameter 2 :     Short Term Fuel Trim (B1) Every 5 Seconds
          Parameter 3 :     Short Term Fuel Trim (B2) Every 5 Seconds (Not Supported By Vehicle)
          Parameter 4 :     Long Term Fuel Trim (B1) Every 5 Seconds
          Parameter 5 :     Long Term Fuel Trim (B2) Every 5 Seconds (Not Supported By Vehicle)

     Comments :     

Davis CarChip Graph of Car Speed . Davis CarChip Graph of Short Term Fuel Trim . Davis CarChip Graph of Long Term Fuel Trim at zero percent


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